Spray shield

ABSTRACT

For use with agricultural sprayers, a unique spray shield is disclosed. The shields are mounted in pairs along the wet spray boom fore and aft in approximately the same plane, thereby shielding the nozzles of the sprayer. The shields are elongate and each is equipped with an air intake opening facing away from the wet spray boom. An air outlet of smaller cross-section is located at the bottom of each shield. As the sprayer moves in a direction against the wind, air enters the intakes of the fore shields and is directed downwardly and outwardly at a greater velocity thereby producing a curtain of air immediately in front of the sprayed area, thereby breaking the wind and avoiding disruption of the spray. Similarly, on the return passage over the land when the wind is blowing from the rear of the implement, the spray shields on the rear of the spray boom entrap the air and turn it downwardly, again creating a curtain of air behind the sprayed area.

FIELD OF THE INVENTION

This invention relates to agricultural liquid sprayers and,particularly, to wind shields for such sprayers.

BACKGROUND OF THE INVENTION

Field sprayers have become increasingly larger with a wide spray area asproduction areas, and farming has become more capital-intensive. Liquidsprayers are used for applying pesticides, herbicides and fertilizers.The timing of such applications is critical at certain periods of theyear.

One of the problems encountered in spraying is that on the prairies orother wide-open areas, there is constant wind which may blow for as longas a week or two at a time, thereby preventing the farmer from carryingout an effective spraying program when and where he wants to.

In order to alleviate this problem, various devices have been developedto reduce drift of the spray caused by the wind. The basic concept hasbeen to provide a shroud or cover over the spray boom to prevent thewind from entering the area being sprayed. Such a structure may comprisea drape, a snow fence type structure, or skirt. Such a device isdisclosed and claimed in Canadian Patent 1,206,126 (McCrea).

Others have tried such things as an inflatable bag structure, such asthat shown in Canadian Patent 1,094,517 (Jones).

Another type of device employs a type of air foil whereby the wind movesalong over the skirt-like structure forcing it downwardly such as thatshown in Canadian Patent 1,225,374 (Rogers).

Still others have attempted to protect the spray by means of an invertedcone around each of the nozzles, such as the Brandt "Wind Cone".

All of the above devices reduce drift to a certain extent, but generallyat the expense of distribution. Furthermore, another serious problemwith such devices is that spray nozzles and spray patterns are concealedfrom the operator by the shield making it difficult for the operator totell if all the nozzles are operating properly. As well, many of thesestructures are extremely expensive to make and cumbersome to assemble,maintain, and clean.

The present invention seeks to solve the spray drift problem byemploying an entirely new principle. Rather than blocking out the windand reducing drift at the expense of distribution, the present inventionemploys the wind to the advantage of the sprayer.

It is an object of the present invention to provide a spray shield thatis inexpensive to make, easy to assemble, and which fits most sprayerswhich employ wet spray booms which are transverse to the direction oftravel in the field position.

It is a further object of the present invention to reduce drift andimprove distribution of spray.

Finally, it is an object of the present invention to provide a sprayshield which will not clog with chemicals and soil that requires littleor no cleaning and maintenance, and still allows the operator to see thespray pattern from the tractor cab.

SUMMARY OF THE INVENTION

Therefore, this invention seeks to provide a spray shield for use withan agricultural liquid sprayer of the type comprising at least oneelongate wet spray boom adapted to spray when said boom is in the fieldposition transverse to the direction of travel;

said spray shield comprising an elongate structure adapted to bepositioned longitudinally adjacent said wet spray boom and having an airintake adapted to be directed horizontally away from said wet sprayboom, and an air outlet adapted to be directed downwards to one side ofsaid spray boom;

said spray shield defining a passageway between said intake and saidoutlet such that during operation, air exiting through said outletproduces a downwardly directed curtain of air, thereby reducing thedisruption of spray.

This invention further seeks to provide a spray shield adapted for useon an agricultural sprayer, said spray shield comprising:

an elongate structure, comprising an air intake which is substantiallyhorizontally directed and an air outlet which is vertically downwardlydirected, one side of said spray shield being concave between saidintake and said outlet and the opposite side being convex between saidinlet and said outlet;

said shield being hollow and defining a passageway of decreasingcross-section between said inlet and said outlet, wherein in operationsaid shield is longitudinally mounted along a wet spray boom of anagricultural sprayer and in substantially the same horizontal plane assaid wet spray boom, thereby directing air from the horizontal planevertically downwards in a curtain.

In the present invention, pairs of elongate spray shields are attachedalong the spray boom fore and aft. Although the shields can be of anylength, the preferred embodiment is to employ sections approximately onefoot long which are jointed together to fit various sections along thewet spray boom. These are mounted throughout the length of the spraybooms. Such shields can be used on both a two-wing sprayer and a centralboom two-wing sprayer, or any combination of the two. Since most modernsprayers raise and lower the wet spray boom from a transport to a fieldworking position, it is necessary to allow the framework connecting thewet spray boom to the dry spray boom to raise and lower withoutcontacting or doing damage to the shields.

The spray shields of the present invention are in an elongate form andhave a concave face and an opposite convex face. An air intake extendsgenerally throughout the length of the shield. In transversecross-section, the shield is curved in the shape of a horn such that theair inlet faces outwardly of the spray boom nozzle. The bottom of theshield has an outlet which also extends along the length of the shield.The shield is a hollow structure, such that when air (wind) enters theintake or inlet it is deflected vertically downwards and outwards fromthe air outlet thus producing an air curtain.

In a preferred embodiment, the outlet is considerably narrower than theinlet and the shield has a decreasing cross-sectional area between theinlet and the outlet. When air enters into the intake or inlet, itincreases in velocity as it leaves the outlet. Below the inlet is aconcave face. The opposite side is convex. The shield extends upwardlyjust above the wet spray boom and downwardly a sufficient distance belowthe nozzle. On the rear side of the spray boom are other shieldsidentical to the front shield.

In an alternative embodiment one or both of the intake and the outletis/are equipped with a baffle and the hollow shield is of constant orvarying cross-section. By adjusting the baffle(s) the size of theopening of the intake or the outlet can be regulated. In other words adecrease in the size of the opening of the outlet, while maintaining aconstant sized opening in the inlet, will result in a correspondingincrease in the velocity of the air exiting the outlet and therebycreate a stronger downwardly directed air curtain.

Spraying with the shields is carried out by pulling the sprayerimplement across the field in either the same direction of the wind, oragainst the wind. It is recommended that spraying is not carried outacross the wind, unless the wind is very light.

The spray shield achieves control of spray drift by redirecting some ofthe wind towards the ground to act as an air curtain. The primary aircurtain is achieved by the air that enters the shield inlet. In thepreferred embodiment, as the air is turned towards the ground, it isforced to speed up by constricting the flow as it approaches the shieldoutlet. A secondary air curtain is created by the air that strikes theshield below the shield inlet. In this area, the flow is forced towardsthe ground by the concave shape of the leading surface of the shield.The secondary air curtain is constricted by wind that strikes it as itmoves down the surface of the shield. Below the spray shield the primaryand secondary air curtains mix together and act as a single air curtain.The air curtain will mix with the wind below the shield, however,because the air curtain is moving faster than the wind at the level ofthe spray shield and the wind loses strength as it approaches theground. This causes the air curtain to bend gently back and enter thecrop canopy in the same region as the spray droplets.

Above the spray shield, the wind is not disturbed and continues past thespray shield without effecting the behaviour of the spray. As long asthe spray boom is perpendicular to the wind direction, the shield caneffectively protect the spray regardless of the direction of therelative wind, that is front or back.

The strength of the air curtain is of course dependent on the relativeground speed of the implement and the speed of the wind. For example, ona day when the wind is light, it is primarily the speed of the vehiclethat will produce the air curtain. Naturally, the force of the aircurtain will be less, when there is less wind. However, on a day withlight winds, it is not necessary to form as strong an air curtain toshield the spray. Conversely, on a day with a strong wind and in thesituation where the vehicle is moving against the wind, a strong aircurtain will develop below the shield. Thus, a strong air curtainprotects the spray when the wind would otherwise create a greaterdisruption of spray.

The shape of the openings and that of the shield can be varied as longas the basic principle is maintained. Naturally, it is preferable tohave a solid air curtain from one end of the sprayer boom to the otherin order to ensure minimum drift and maximum distribution.

BRIEF DESCRIPTION OF THE INVENTION

The invention will be more fully described in connection with thefollowing drawings, wherein:

FIG. 1 is a transverse cross-section of a wet spray boom having a sprayshield mounted on either side of it;

FIG. 2 is a drawing similar to FIG. 1 wherein the direction of the windhas changed;

FIG. 3 is a perspective view of a pair of spray shields, each mounted oneither side of a wet spray boom;

FIG. 4 is a cross-section of the main wing boom, dry spray boom and wetspray boom of an agricultural sprayer showing the wet spray boom in boththe operating and the transport position;

FIG. 5 is a top view of a left wet spray boom with pairs of shieldsmounted thereon, said boom being in the transport position;

FIG. 6 is a top view of the right wing boom of an agricultural sprayer,showing the wet spray boom in the field position;

FIG. 7 is a rear view of the wet and dry spray boom and the left mainwing boom of an agricultural sprayer in the transport position;

FIG. 8 is a similar drawing illustrating the wet spray boom in the fieldposition; and

FIG. 9 is a top view of an agricultural liquid sprayer having a rightmain boom in the field spraying position and the left main wing boom inthe transport position.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, a pair of spray shields 1 are mounted one on each side of awet spray boom 7. The direction of the sprayer implement is shown as (A)and the direction of the wind is shown as (B). In other words, thedirection of the spray implement is towards the wind and the spray boomsare arranged transverse to the direction of the wind and transverse tothe direction of the power source. The spray shield 1 comprises an airintake opening 2 and an air outlet opening 3. Although not shown in FIG.1, these openings extend throughout the length of the shield 1. Theshield 1 is mounted on a frame 4 which is attached to a block 5 throughwhich passes a clamp 6 which secures the frame 4 to the wet boom 7.

In operation, the implement is towed by a suitable power source such asa tractor or a truck, in the direction marked as (A). Preferably, thevehicle is towed in a direction towards the prevailing wind shown inFIG. 1 as (B). Air enters the intake opening 2 at approximately the samespeed as that of the vehicle added to the velocity of the oncoming wind(B). As the air passes through the spray shield 1, it is constrictedthereby increasing in velocity when it leaves the outlet opening 3thereby producing a downwardly directed primary air curtain marked as 9.Below the opening, air marked as 10 is deflected downward by the concavelower portion of the spray shield and forms a secondary curtain of air.The secondary curtain of air joins together with the primary curtain ofair. This curtain of downwardly directed air is strong enough to deflectthe remaining wind below the shield shown as 11 such that it is alsodeflected downwards. The inertia of the wind and the forward movement ofthe vehicle (A) tend to press the air curtain slightly rearwardly as itapproaches the ground or crop at a point shown as 12.

The spray from the sprayer 8 is directed downwardly and forwardly atapproximately a 20° angle to meet the downwardly directed air curtainnear the ground 12. In this manner, the spray is basically undisturbeduntil it actually reaches the crops.

In FIG. 1, an alternative embodiment of the invention is shown in theleft spray shield. Adjustable baffles 23 and 25 are located near theinlet and outlet, respectively, and are pivotally adjustable on pivots22 and 24, respectively. Obviously, by adjusting the baffles, the rateof flow of the curtain of air exiting the outlet can be varied.

As everyone is aware, it is not practical to always spray in a directiontowards the oncoming wind. When the operator reaches the end of thefield, it is necessary to turn around and spray in the oppositedirection. FIG. 2 depicts such a situation wherein the sprayer is movingin the direction marked as (A) and the wind is moving in the samedirection marked as (B). In other words, the wind is blowing towards therear of the implement. Depending of course on the speed of theimplement, air will enter the shield 1 through opening 2 and produce anair curtain marked as 9 or enter through opening 2(a) of rear shield1(a) and leave through outlet opening 3(a). Thus in the manner shown inFIG. 1, a first curtain of air 9(a) and a secondary curtain 10(a) isproduced. The two curtains together turn the remainder of the wind 11(a)downwards. Any wind blowing above the wet spray boom shown (line (B))passes unobstructed above the spray shields.

FIG. 3 is a perspective view of a pair of spray shields 1 and 1(a)mounted along a wet spray boom 7 by means of a frame 4, block 5 andclamp 6. FIG. 3 illustrates the air intake opening 2 and air outletopening 3 and front deflection face 15 and ends 14. When the wind blowsbelow the opening 2 it strikes deflector face 15 and is forceddownwardly in a secondary curtain of air.

FIG. 4 is a transverse cross-section of a main wing boom of a sprayerimplement illustrating in dotted lines and marked as (U) the wet sprayboom 7 in the upper transport position and representing in solid linesand marked as (D) the wet spray boom in the field operating position.One notes that the spray shields 1 and 1(a) are always substantiallyhorizontally aligned with the wet boom 7. By means of adjustment rod 17and fixed strut 16 the nozzles 8 are always facing 20° towards thedirection of travel. FIG. 4 also shows support caster wheel 20, mainwing boom 19 and the dry spray boom 18.

In FIG. 5, one views the left main wing boom 19 of a sprayer from a topview in the transport position. One notes that the support caster wheel20 is aligned with the longitudinal axis of the main wing boom 19. Onealso notes that because of struts 16 which attach the dry spray boom(not visible in FIG. 5) to the wet spray boom 7, it is necessary thatthe spray shields 1 and 1(a) terminate adjacent each strut in order toavoid contact with the support struts 16.

FIG. 6 is an upper top view of a right-hand wing boom 19 of a sprayer inoperating position. One notes that the support caster wheel 20 issubstantially perpendicular to the wing boom 19 which is transverse tothe direction of travel of the implement. One can see clearly in FIG. 6how the fixed struts 16 which connect the dry spray boom 18 to the wetspray boom 7 must have clearance with the spray shields 1 and 1(a)located on either side thereof, in order for the wet spray boom to belowered and raised between the transport and field positions.

FIG. 7 is a rear view of the wet spray boom 7 in transport positionshowing rear spray shield 1. The front spray shield 1(a) is hidden fromview. One notes also that the dry spray boom 18 is in front of the mainwing boom 19.

In FIG. 8, the wet spray boom 7 is in the lowered field position. Againthe front spray shields 1(a) are hidden from view.

FIG. 9 is an overhead view of a complete agricultural sprayer whereinthe right main wing boom 19 is in the field transverse position and theleft main wing boom 19 is in the transport position. One notes the sprayshields 1 and 1(a) lying adjacent the entire length of the wing alongwet spray boom 7. This arrangement ensures that a substantially unbrokendownwardly directed air curtain exists throughout the length of thespray boom. The dry spray boom 18 on the left wing boom which is in thetransport position is almost directly below the wet spray boom 7 andtherefore cannot be seen.

What I claim as my invention is:
 1. A spray shield for use with anagricultural liquid sprayer of the type comprising at least one elongatewet spray boom adapted to spray when said boom is in the field positiontransverse to the direction of travel;said spray shield comprising anelongate structure adapted to be positioned longitudinally adjacent saidwet spray boom and having an air intake adapted to be directedhorizontally away from said wet spray boom, and an air outlet adapted tobe directed downwards and forwards of said spray boom; said spray shielddefining a passageway between said intake and said outlet such thatduring operation, air exiting through said outlet produces a downwardlydirected curtain of air in front of the spray in the direction of travelthereby reducing the disruption of spray.
 2. A spray shield for use withan agricultural liquid sprayer of the type comprising at least oneelongate wet spray boom adapted to spray when said boom is in the fieldposition transverse to the direction of travel;said spray shieldcomprising an elongate structure adapted to be positioned longitudinallyadjacent said wet spray boom and having an air intake adapted to bedirected horizontally away from said wet spray boom, and an air outletadapted to be directed downwards to one side of said spray boom; saidspray shield defining a passageway decreasing in cross-section betweensaid intake and said outlet such that during operation, the velocity ofthe air exiting through said outlet is greater than the velocity of airentering said inlet thereby producing a downwardly directed curtain ofair thereby reducing the disruption of spray.
 3. A spray shield asclaimed in claim 2, wherein said intake and said outlet extendsubstantially throughout the length of said shield.
 4. A spray shield asclaimed in claim 3, wherein said intake is larger than said outlet. 5.An agricultural sprayer comprising a plurality of spray shields asclaimed in claim 2, said spray shields being arranged along a wet sprayboom on either side thereof with said air intakes directed away fromsaid wet spray boom in substantially the same horizontal plane, and airoutlets directed downwardly and outwardly of said wet spray boom suchthat, when in operation, wind approaching said wet spray boom fromeither side is directed downwardly thereby creating a curtain of air oneither side of said wet spray boom thereby reducing the disruption ofspray.
 6. An agricultural sprayer as claimed in claim 5, comprising atleast two elongate wet spray booms adapted to extend transversely to thedirection of travel of said sprayer, wherein said spray shields aremounted in pairs, one on each side of said wet spray boom, throughoutthe length thereof.
 7. A sprayer as claimed in claim 6, wherein the sideof said shields remote from said wet spray booms are concave betweensaid air intakes and said air outlets such that, when in operation, windblowing toward said wet spray boom is directed downwardly.
 8. A sprayeras claimed in claim 7, wherein the sides of said shields adjacent saidwet spray booms are convex between said intake and said outlet.
 9. Asprayer as claimed in claim 5, wherein said air intake and said airoutlets extend throughout the length of said shields.
 10. A sprayer asclaimed in claim 9, wherein the cross-section of said air intakes isgreater than the cross-section in all dimensions of said air outlets.11. A spray shield adapted for use on an agricultural sprayer, saidspray shield comprising:an elongate structure, comprising an air intakewhich is substantially horizontally directed and an air outlet which isvertically downwardly directed, one side of said spray shield beingconcave between said intake and said outlet and the opposite side beingconvex between said inlet and said outlet; said shield being hollow anddefining a passageway of decreasing cross-section between said inlet andsaid outlet, wherein in operation said shield is longitudinally mountedalong a wet spray boom of an agricultural sprayer and in substantiallythe same horizontal plane as said wet spray boom, thereby directing airfrom the horizontal plane vertically downwards in a curtain.
 12. A sprayshield for use with an agricultural liquid sprayer of the typecomprising at least one elongate wet spray boom adapted to spray whensaid boom is in the field position transverse to the direction oftravel;said spray shield comprising an elongate structure adapted to bepositioned longitudinally adjacent said wet spray boom and having an airintake adapted to be directed horizontally away from said wet sprayboom, and an air outlet adapted to be directed downwards to one side ofsaid spray boom; said spray shield defining a passageway between saidintake and said outlet; at least one of said intake and said outletbeing equipped with a baffle adapted to increase or decrease the openingof at least one of said intake and said outlet, such that the velocityof the air passing through said outlet will vary from that passingthrough said inlet; wherein, in operation air exiting through saidoutlet produces a downwardly directed curtain of air thereby reducingthe disruption of spray.